I bought my first "real" prewar Lionel Standard Gauge tinplate on an impulse. I had previously bought a modern Lionel Standard Gauge Hiawatha, more for my collection of Hiawathas than out of any real interest in Standard Gauge, but no other tinplate. I was at a train show before it opened, setting up my tables, and I took a stroll around the place to see what everyone else had. There was an old guy there with some tinplate, including a set with a 390E in amazing condition. The price was right, I couldn't resist and I bought the set on the spot. Half an hour later I walked by that table again and noticed a couple of guys who I knew as big-time Standard Gauge collectors weeping and wailing that it had sold before they made up their mind to buy.
That 390E is still one of the smoothest running tinplate engines I have. In particular, it has the quietest mechanical E-unit I've ever seen, prewar or post. The rest of the set was ordinary - peacock gondola, green and orange stock car, green and red caboose - but in good condition. I still think I got a great deal on that set and I probably will never sell it, although I seldom run it any more.